Republican hopefuls' fate in the balance

The polls have had him consistently in the lead, some by 20 points or more.

The polls in Iowa had him in the lead too, and only a few people predicted he'd lose. He did.

And the polls in New Hampshire are much more indicative than predictive.

The problem they have is that many voters don't make their mind up until the day of the primary. And that causes upsets.

Trump needs a win here.

You can't keep talking about how great you're going to be and be rejected in the the first two places people vote.

The margin of victory is important, too. A slim three-five point win is still a win, but it might feel like a loss.

Will Marco Rubio's terrible debate performance hit him in the polls?

The Florida senator had a dreadful night in Manchester on Saturday.

Slammed for being inexperienced and inauthentic, he repeated the same Obama attack line four times.

That allowed Chris Christie to highlight that Rubio spoke in 25-second bursts approved by advisers and couldn’t stop.

I'm reluctant to draw a direct impact from the debates to the polls - remember most of us thought Donald Trump won the last Iowa debate by not turning up - but the Christie attack left Rubio wounded and vulnerable.

It certainly hit the momentum he generated from a better-than-predicted finish in Iowa.

Some polls here say he’ll finish third. If he doesn't, he has a problem.

How will the candidates who really started their campaigns in New Hampshire fare?

Three candidates - the governors, as they're known collectively - have banked on a good New Hampshire performance to kick-start their campaign.

But Chris Christie from New Jersey, Ohio's John Kasich and Jeb Bush from Florida are all chasing the same swath of voters.